Self-propelled machines, such as lawn mowing machines and the like, often provide handles on which controls are mounted for engagement and/or manipulation by operators or users of such machines. In particular, a “walk behind” type, self-propelled mowing machine typically has a handle extending behind a power plant or other main operative assembly of the machine for gripping by an operator as the operator walks behind the machine during movement thereof in a forward direction. Typically, one or location for the user to manipulate while gripping the handle and operating the machine.
One such control is the operator presence control or “dead man” control, which generally includes a spring-biased handle which can be grasped by the operator during normal operation of the machine to enable the motor of the machine. If the operator presence control handle is thereafter released, the machine action is rapidly terminated for reasons of safety. Another well-known control is the speed control, which for self-propelled mowing machines is generally connected to a variable speed transmission associated with the engine and controls the speed of the self-propelled traction wheels. These speed controls typically comprise a lever pivotally mounted onto the machine handle such that the speed of the self-propulsion can be controlled by moving the lever back and forth, which often requires the operator to remove one hand from the handle in order to operate the speed control.
These independent systems also typically require the operator to control two or more separate functions while operating the machine. Many consumers of self-propelled machines prefer a minimum number of control mechanisms requiring manipulation during operation of such machines in order to simplify use of the machines. A solution to this problem, a variable speed twist control, is disclosed in commonly owned U.S. patent application Ser. No. 11/125,843, the disclosure of which is incorporated herein.
Unfortunately, due to the different heights of the operators that use such twist control systems and due to the different ways that operators may operate such twist control systems, a single orientation of the control system on the handle of the lawn mowing machine may not be optimal for use and comfort for every operator. Therefore, it would advantageous to employ an adjustable variable speed twist control that is operatively connected to a variable speed transmission of a self-propelled mowing machine to control the speed of propulsion. The adjustable twist control can allow an operator to adjust the angle of the twist control on the handle of the mowing machine to better accommodate individual users and their preference for ease and comfort of operation.